#include "base64.h"

static uint8 alphabet_map[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static uint8 reverse_map[] =
{
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 62, 255, 255, 255, 63,
	52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255, 255, 255, 255, 255,
	255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
	15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 255, 255, 255, 255, 255,
	255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
	41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 255, 255, 255, 255, 255
};

// //GB2312到UTF-8的转换
// char* G2U(const char* gb2312)
// {
// 	int len = MultiByteToWideChar(CP_ACP, 0, gb2312, -1, NULL, 0);
// 	wchar_t* wstr = new wchar_t[len + 1];
// 	memset(wstr, 0, len + 1);
// 	MultiByteToWideChar(CP_ACP, 0, gb2312, -1, wstr, len);
// 	len = WideCharToMultiByte(CP_UTF8, 0, wstr, -1, NULL, 0, NULL, NULL);
// 	char* str = new char[len + 1];
// 	memset(str, 0, len + 1);
// 	WideCharToMultiByte(CP_UTF8, 0, wstr, -1, str, len, NULL, NULL);
// 	if (wstr) delete[] wstr;
// 	return str;
// }
// //UTF-8到GB2312的转换
// char* U2G(const char* utf8)
// {
// 	int len = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, NULL, 0);
// 	wchar_t* wstr = new wchar_t[len + 1];
// 	memset(wstr, 0, len + 1);
// 	MultiByteToWideChar(CP_UTF8, 0, utf8, -1, wstr, len);
// 	len = WideCharToMultiByte(CP_ACP, 0, wstr, -1, NULL, 0, NULL, NULL);
// 	char* str = new char[len + 1];
// 	memset(str, 0, len + 1);
// 	WideCharToMultiByte(CP_ACP, 0, wstr, -1, str, len, NULL, NULL);
// 	if (wstr) delete[] wstr;
// 	return str;
// }

// uint32 base64_encode(char* input, uint8* encode)
// {
// 	//1、包含中文的字符串 字符编码（windows默认是gbk）转换成unicode
	
// 	//2、字符编码方式是utf-8的二进制
// 	// uint8* text = (uint8*)G2U(input);
// 	uint32 text_len = (uint32)strlen((char*)input);

// 	uint32 i, j;
// 	for (i = 0, j = 0; i + 3 <= text_len; i += 3)
// 	{
// 		encode[j++] = alphabet_map[text[i] >> 2];                             //取出第一个字符的前6位并找出对应的结果字符
// 		encode[j++] = alphabet_map[((text[i] << 4) & 0x30) | (text[i + 1] >> 4)];     //将第一个字符的后2位与第二个字符的前4位进行组合并找到对应的结果字符
// 		encode[j++] = alphabet_map[((text[i + 1] << 2) & 0x3c) | (text[i + 2] >> 6)];   //将第二个字符的后4位与第三个字符的前2位组合并找出对应的结果字符
// 		encode[j++] = alphabet_map[text[i + 2] & 0x3f];                         //取出第三个字符的后6位并找出结果字符
// 	}

// 	if (i < text_len)
// 	{
// 		uint32 tail = text_len - i;
// 		if (tail == 1)
// 		{
// 			encode[j++] = alphabet_map[text[i] >> 2];
// 			encode[j++] = alphabet_map[(text[i] << 4) & 0x30];
// 			encode[j++] = '=';
// 			encode[j++] = '=';
// 		}
// 		else //tail==2
// 		{
// 			encode[j++] = alphabet_map[text[i] >> 2];
// 			encode[j++] = alphabet_map[((text[i] << 4) & 0x30) | (text[i + 1] >> 4)];
// 			encode[j++] = alphabet_map[(text[i + 1] << 2) & 0x3c];
// 			encode[j++] = '=';
// 		}
// 	}
// 	encode[j] = 0;
// 	return j;
// }

int base64_decode(const uint8* code, uint32 code_len, char* str)
{
	uint8 plain[1024];
	assert((code_len & 0x03) == 0);  //如果它的条件返回错误，则终止程序执行。4的倍数。

	uint32 i, j = 0;
	uint8 quad[4];
	for (i = 0; i < code_len; i += 4)
	{
		for (uint32 k = 0; k < 4; k++)
		{
			quad[k] = reverse_map[code[i + k]];//分组，每组四个分别依次转换为base64表内的十进制数
		}

		assert(quad[0] < 64 && quad[1] < 64);

		plain[j++] = (quad[0] << 2) | (quad[1] >> 4); //取出第一个字符对应base64表的十进制数的前6位与第二个字符对应base64表的十进制数的前2位进行组合

		if (quad[2] >= 64)
			break;
		else if (quad[3] >= 64)
		{
			plain[j++] = (quad[1] << 4) | (quad[2] >> 2); //取出第二个字符对应base64表的十进制数的后4位与第三个字符对应base64表的十进制数的前4位进行组合
			break;
		}
		else
		{
			plain[j++] = (quad[1] << 4) | (quad[2] >> 2);
			plain[j++] = (quad[2] << 6) | quad[3];//取出第三个字符对应base64表的十进制数的后2位与第4个字符进行组合
		}
	}
	plain[j] = 0;
	// char str[1024] = "";
	strcpy(str, (char*)plain);
	// strcpy_s(str, sizeof(plain), U2G(str));
	return j;
}